The present invention relates to an automatic transmission control unit and more particularly to an automatic transmission control unit for an automobile which transmits the driving force from an engine to axles.
A conventional automatic transmission control unit has been used by an automobile having a system which automatically changes the revolutions per minute (rpm) of the engine while transmitting the driving power to the axle. Further, to optimize transmission time, the automatic transmission control unit controls forces working on friction members according to the running status of the automobile. Substantially, the conventional automatic transmission control unit controls the hydraulic pressures working on the engaging and disengaging friction members at a suitable timing.
The conventional automatic transmission control unit determines the disconnecting timing and hydraulic pressure just before the racing. However, because of manufacturing tolerances of products, it has frequently occurred that, when the actual disconnecting hydraulic pressure is lower than the instructed value, a racing occurs and the friction members are quickly damaged.
To eliminate this problem, for example, Japanese application patent laid-open publication No. Hei 10-47465 (1998) has disclosed a method of preventing racings of the engine by increasing the disconnecting hydraulic pressure when detecting a racing. For another example, Japanese application patent laid-open publication No. Hei 10-184882 (1998) has disclosed a method of preventing racings of the engine by increasing the connecting hydraulic pressure when detecting a racing.
The systems disclosed in the above stated Japanese application patent laid-open publication Nos. Hei 10-47465 (1998) and Hei 10-184882 (1998) singly increase the disconnecting or connecting hydraulic pressure when detecting the racing. Therefore, if the actual hydraulic pressure goes higher than the instructed value, the driver may feel a comparatively great pullback shock or abrupt kickback.
The main object of the present invention is to provide an automatic transmission control unit which detects and reduces racings for smooth and shockless transmission.
(1) The present invention relates to a control unit for controlling an automatic transmission system of an automobile which transmits a driving power from the output shaft of the engine to the transmission system through friction members, controls to disconnect and link together said friction members, and controls gear ratios of said transmission.
In order to realize the above object according to the present invention, the automatic transmission control unit in accordance with the present invention comprises means for detecting a starting point of a torque phase of said transmission, means for detecting a racing of the engine is racing, and control means which changes the disconnecting or connecting hydraulic pressure or timing in the next and later transmission according to whether the racing detected by said racing detecting means is before or after the torque phase starting point which is detected by said torque phase detecting means.
When detecting a racing, this configuration checks whether the racing occurs before or after the torque phase starting point and controls the disconnecting or connecting hydraulic pressure or timing according to it. This can reduce racings and provide smooth and shockless transmission.
(2) Preferably in (1), said control means is designed to increase the disconnecting hydraulic pressure in the next transmission when the racing detected by said racing detecting means is before the torque phase starting point which is detected by said torque phase detecting means.
(3) Preferably in (1), said control means is designed to increase the connecting hydraulic pressure in the next transmission when the racing detected by said racing detecting means is after the torque phase starting point which is detected by said torque phase detecting means.
(4) Preferably in (1), said control means is designed to delay the disconnecting timing in the next transmission when the racing detected by said racing detecting means is before the torque phase starting point which is detected by said torque phase detecting means.
(5) Preferably in (1), said control means is designed to advance the disconnecting timing in the next transmission when the racing detected by said racing detecting means is after the torque phase starting point which is detected by said torque phase detecting means.
(6) Preferably in (1), said control means is designed to reduce the disconnecting hydraulic pressure in the next transmission when said racing detecting means detects no racing.
(7) Preferably in (1), said control means is designed to advance the disconnecting timing in the next transmission when said racing detecting means detects no racing.